1 : (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work; "entropy increases as matter and energy in the universe degrade to an ultimate state of inert uniformity"
2 : the cardinal compass point that is at 180 degrees
3 : 1/60 of a minute; the basic unit of time adopted under the Systeme International d'Unites
4 : the cardinal compass point that is at 180 degrees
5 : a unit of conductance equal to the reciprocal of an ohm
